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07:35
If you hadn't been offered the job the answer would have been clear to me:
That they didn't want you to take the job,
but that something was forcing them to interview you.
For example they had a favorite picked out from prior information;
but policy required them to conduct at least 2 interviews
But since they did offer you the job this seems less likely.
Not impossible, just that it would require a really convoluted attempt to loop hole through a policy.
Such as it being required that someone turn down an offer at a particular pay-rate before they can start offering higher than that pay rate to future applicants.

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